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Discussion Starter · #1 ·
Here's the trailer. It's a smaller toy hauler with a 7K lb GVR. Did not weight it but empty it is in the lower 5's. Large generator/inverter mounted on the tongue and twin 30# gas bottles probably get tongue weight around 800 lbs. That's a guess as it crushed my scale testing.



Picked out a 26+ mile loop to run my Ecodiesel pulling the trailer. Mostly flat, there are a few rolling elevations, no traffic lights and speeds can be anything you want. I mostly went 65 mph but often went 70 mph. On a truck pass I pulled over 80 mph.

First test was to hook up with no equalizer bars to take weight off the truck. I call it the "hook and book". Sorry for the smear on the camera lens. All pictures have it.



It dropped the rear 2 1/2" on hookup. The Timbren bumper stops are contacting the bottom with a tiny bit of compression. Immediately I did not like it. The truck moved a bit and did bounce around just a little bit. Way better than every other 1/2 ton truck I ever rode in while towing. It was not right for me as I'm used to my old 2500 Cummins. It was reasonably stable at speed.

Power was fine. The engine is more than enough to pull and pull well. I used tow-haul mode on this test and was shocked at how high the rpm's were. The sound is not "manly" like my Cummins. I am spoiled. This thing sounds cheesy at higher rpm's. This truck needs a lesson from Harley Davidson. Throughout this test I was uncomfortable listening to it.

There is a bit of a squat so I watched rear tire temperature. Both went from 45 to 50 psi quickly. During test 2 with equalizer bars, they stopped at 49 psi but sure did rise more than I expected or ever saw.

You don't want to hear this stuff? Try this - the fuel mileage sucked.



Now do I have your attention?

It's no better or maybe worse than my Cummins was. I was both shocked and disappointed. Not despondent. It's at least as good as my Cummins. I really expected more. The truck is oh so good without a trailer and I did read many other tests that spoke of higher fuel mileage. Maybe it was the tow-haul mode. It is a miserable thing that keeps you out of the higher gears, the rpm's up and seems oh, so busy.

Test two was with a new head, equalizer bars set just a little. The trailer also sat almost level. It looked like this.



See the large inverter and twin bottles? I set the bars to drop two inches. Do want the rear tires making solid contact. Make it light with lots of tension and the rear tires skip and tear off. Off I went with NO tow-haul mode this time.

Immediately I liked the lower rpm sound. Never on this same route did I ever get it to go into 8th gear. It will not go there but does try to hang onto 7th, rather than run in 6th. 3.55's for those interested. Went 65, went 70, watched and listened to the rpm's. Lower mostly but it can and does go up at times. Felt like I needed more pedal to keep the speeds up. Acceleration was no different between the modes. There's plenty of motor here.

I got agitated at an 18 wheeler doing 60 and hammered it down. Got to 80 mph towing and passed that sucker. Not powerful up there but adequate and it moved right around that truck. Tried hard to get to 8th. Could not do it. Anyway, here's the answer. Note there is no tow-haul light on this so I am sure it's the right picture.



Couple tenths LESS in fuel mileage. 53 miles of tow testing for both you and me. I'm not happy. It's disappointing. Frankly, I never expected something like this. Wife is pissed. I am making sure she knows it's not significantly worse than the Cummins. It also does tow this trailer with great control if you use the equalizer bars. Without those bars it's not nearly as stable but usable.

Oil temps. stayed in the 240 degree range, Coolant was in the 220's. I have more but his is enough. It tows like a 1500 with plenty of engine to get the job done.

Knowing what I know now, I would still have bought this configuration. My old truck was high mileage and over 10 years old. The new Cummins would tow better with the same mileage but not towing would be much less fuel mileage. It would also have cost more to have bought it. Could have gotten another manual transmission with the Cummins. That I miss. That and the "manly" sound of that combination instead of this VM whining.

You have cheese to go with this whine?
 

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Great report capt! That's crazy I was getting better milage towing 9K+ before the pump let go, I was avging 16.7L/100km or about 13mpgs....

Seems off.... that's really low mpg's headwinds?
 

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Discussion Starter · #3 ·
Looking for feedback Chris. My take is most all camper-type trailers create so much wind resistance they eat right into the fuel mileage big time. Every time I see a towing test they are towing car haulers, boats, piles of rocks in open trailers etc. None offer the wind resistance of a flat trailer.

Now there are some tests with flat fronted trailers out there. RangerGress did one. He did way better than me.

I can only report. I am not going to fabricate.
 

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I towed more trailer and got better mpg doing it. We must be overlooking something here. I was at 64mph except I allowed the truck to slow up a bit when climbing rolling hills. I got 14.4mpg for a 440mile trip, that's an honest 1mpg better than my buddy with same trailer, speed and route, in his late model Cummins. Did you hold a relatively steady speed and if so, what was it?
 

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Discussion Starter · #6 ·
No. Changed speeds to test rpm's at speed. Doubt I went more than 4 miles at a constant speed. Mostly went 65 mph but did run it up often. Not normally below 50 mph except for a couple miles at the beginning or the end. Also felt the truck would slow down if I did not keep my foot into it a bit. Never to the floor but out of tow-haul it felt like it was lugging to hold speed. It did seem to run easier when the rpm's were over 2,000, even below 60 mph.

My trailer does have a front angled back a bit. Yours is in a wedge shape. That might be a push.

You did 25% better with fuel mileage than me and had a solid ton more gross weight. Now you see why I'm disappointed?
 

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Discussion Starter · #7 ·
Sorry Gleb. My tires are stock. Don't know what "P Rated" is.
 

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P rated are essentially passenger car tires; LT is a "light truck" tire and significantly 'stronger' with higher payload rating and construction... :)
 

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I blame the 3.55's here, it would have reduced your lugging to have the .92's and thus increased your mileage while towing, keeping you in the torque better with lower RPM's.
 

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P rated are essentially passenger car tires; LT is a "light truck" tire and significantly 'stronger' with higher payload rating and construction... :)

you can tell immediately looking on your tire you'll see something like "P265/70/17" which tells you its just a standard passenger tire, albeit a big one... when it comes time to replace or if you know you're going to tow, highly HIGHLY recommend people get those P rated pieces of rubber off their trucks and get a good LT tire... they will handle the weight and in all likely hood, last you longer, than a P rated tire on a truck...
 

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Discussion Starter · #11 ·
P265/70 r17. Standard load.

At marina now. Had to look. Got 28 mpg going here.
 

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I don't think a 26 mile loop is long enough for an accurate test and you talk of punching it and going to 80 with both tests and changing speeds all these things have a substantial affect on mileage especially on that short of a loop. I think you should wait for a true tow before you know for sure.
 

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I don't think a 26 mile loop is long enough for an accurate test and you talk of punching it and going to 80 with both tests and changing speeds all these things have a substantial affect on mileage especially on that short of a loop. I think you should wait for a true tow before you know for sure.
I agree with this 26 miles or even 50 is a short trip. When you change speed often I'm sure your instant MPG went down to 6 or so. Do this a bunch with no load and watch your MPG drop.
 

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Interesting report Captainmal. I'm shocked at those numbers too. Now I want to hook up my camper and take a long trip to see how my truck reacts under load. Certainly not worse than the Hemi at 12mpg, I hope. Since I don't pull the camper that much I'll have to live for those high numbers when not towing.
 

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Thank you for the report Capt. I for one would never tow at that speed, especially since my ST rated tires on trailers are rated at 65mph. I would love to see how this will do at 60 MPH hauling at travel trailer with the 3.92 gears.
 

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I towed more trailer and got better mpg doing it. We must be overlooking something here. I was at 64mph except I allowed the truck to slow up a bit when climbing rolling hills. I got 14.4mpg for a 440mile trip, that's an honest 1mpg better than my buddy with same trailer, speed and route, in his late model Cummins. Did you hold a relatively steady speed and if so, what was it?
Are you towing an open or an enclosed trailer???
 

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Discussion Starter · #17 ·
Closed. Look at the pictures.

On a discussion with a knowledgable guy now. Beer certified.
 

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Tires were changed on my way home from the dealership. To me that's the first weakest link of course then you lose some mileage all around. The air suspension helps I believe since I paid for it I want to. I don't have much familiarity with the Timberens but on my Tundra I had the Firestone airbags and they served well for $100. None of this helps you have the Cummins or improve the fuel mileage but you get to keep your smooth ride and your empty mpg. That has been my goal to land in a manageable middle. For me so far I feel like I have achieved that.
The one other weak leak I may deal with later is brakes.
 

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just filled tank today and EVIC was off by 3 mpg , the best way to test would be to fill tank before test then refill after and hand calculate
 

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Discussion Starter · #20 ·
Agree that the best fuel mileage check would be a long tow and hand calculation. My EVIC seems to be quite accurate. No real way to tell but I do know I used almost a 1/4 tank doing those tests today.
 
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